I know there are a few instances where this is useful.

I asked specifically when I want to spectate a friend's match.
My friends have matches all the time, and I would gladly spectate them if I knew what was going on and I would see the player's relative strength, not absolute strength.
As it is, I find no enjoyment in spectating a match where all the players have 9* (or 1* if watching lower league)

So there are already a bunch of steps you can take where you can see their stars relative to their level (like you described for assoc members), it wouldn't be too hard (and I think it would benefit everyone) if the same happened when I click to spectate a match. because when I do so it's clear I want to enjoy the match and see the players, I don't want to negociate contracts or whatever.
Or have an option for those who want to see the real stars.

It's the same when I look at upcoming matches. All I see is 200%+ for both players. How does that help me?
Or at least substitute a useless information (like 9* or 200%+) and just give me the option to see the raw number (this guy has a 74 rating, the other guy has 78)

I'm in these screens because I look at a friend, not a cup opponent (I understand that once in a while it could be both, but put away functionality just because some might confuse the numbers once in a blue moon?)